What are dive watches?


It’s a remarkable feat of modern watchmaking that there’s even such a thing as a “dive watch.” In an age of electronics, the idea that you can take a piece of kit several hundred feet under the surface of the ocean seems almost novel. 

Dive watches, however, aren’t just watches that will keep working if you plunge them in water. They have to meet specific international standards before they can attain the moniker. If they don’t, then sorry, they are not technically dive watches. 

What are dive watches? 

Dive watches are different from “waterproof” or “water-resistant” watches. Dive watches are also different from watches that claim to be water-resistant up to ten, thirty or fifty meters. They have a precise definition set out by the ISO 6425 international standard. 

The standard says that you can only call a dive watch a dive watch if it works in depths of more than about 100 meters. The reason it’s “about” 100 meters is that the actual unit the ISO uses is the “megapascal” - the amount of water pressure that the watch experiences in any given environment. ISO 6425 standards say that a dive watch must be able to withstand 1.0 megapascal (or 10 bar in the more customary units). In other words, it’s got to be immensely robust - far more so than watches rated for dives up to fifty meters. 

As a result of the ISO 6425 standard, you'll see lots of watches that look like divers models, but aren't. It's a popular style, so many "fashion" brands build watches that look like a diving watch but have minimal water resistance. For a lot of people that doesn't really matter - how many people actually dive in their watches? But for some, just knowing that a watch is able to survive at 200+ metres gives them the satisfaction of knowing that their watch is well made. Even if they won't dive in it, they'll trust it.

Are Dive Watches Rare?

While watches with dive rating of up to fifty meters are a dime a dozen, authentic dive watches aren’t. The reason for this is how the pressure of water changes as you go to deeper and deeper depths, and the more advanced and expensive manufacturing required as a result. 

Hamtun Kraken H2 diving watch

Water pressure in the ocean increases by around 14.5 pounds per square inch for every ten meters that you descend. That means that true diving watches have to withstand more than 145 pounds per square inch AND continue to work flawlessly, with the internal mechanisms unaffected. 

When you think about that, you quickly see how a genuine dive watch is a real feat of engineering. Creating the structures and mechanisms in the clock that allow it to work flawlessly at vast depths is a substantial challenge, and usually costly to do. It’s one of the reasons why there are so few genuine dive watches (when compared to fashion watches) in existence in the world today. Making the things is tough and costs money. 

Even more remarkably, many dive watches exceed ISO 6425 standards considerably. Many dive watches will continue working to depths of three hundred meters, or about 260 meters deeper than the average recreational scuba diver.

Professional diver Herbert Nitsch holds the current world record for a no-limits apnea. Back in 2007, he managed to get down to 214 below sea level before having to surface. Thus, a 300-meter-rated dive watch would have suited him down to the ground. 

Why Make Such Extraordinary Instruments? 

You might ask the question of why you would both making such extraordinary instruments. If so few people can reach depths of fifty meters, let alone two hundred, what’s the point? 

It all goes back to the history watches and the need for devices that could withstand the effects of water. Up until about the 19th century, you had to keep timepieces away from the elements. Not only would water disrupt their sensitive internal mechanisms, but so too would things like dust. Keeping them functional was a nightmare. 

For nineteenth-century explorers, this was a problem. Intrepid individuals setting off for the deserts, ice caps and jungles needed timepieces that allowed them to track their movements and schedule. Watchmakers, therefore, began to experiment with the first “dust-resistant” mechanisms and casing and marketed them as explorer watches. Waterproofing first emerged as a kind of accidental byproduct of this process. The dustproof watches seemed to work well for nineteenth-century divers who put them in their helmets to keep track of how long they’d been underwater. 

As diving (and exploring) grew in popularity at the starts of the twentieth century, more industrial watchmakers began experimenting with designs that would provide improved waterproofing. In 1926, Rolex introduced the aptly-named Oyster watch which featured a hermetic seal. The following year, Mercedes Gleitze attempted to cross the English Channel with the watch attached to a ribbon around her neck. The watch survived for more than ten hours in the water and came out ticking perfectly. 

Rolex Submariner diving watch


A decade later, Omega began distributing the first commercially-available dive watches, but the run volumes were small. It was only during and after the second world war, with the explosion in the number of submariners across the globe, that dive watches found more practical uses. The French and US Navies, for instance, began distributing dive watches to their crews in the hope that it would provide them with a way to tell the time, even if they were stranded below meters of brine.

Omega diving watch

Throughout the following decades, dive watches became ever more capable. With the growth of professional scuba diving and the need for people to be able to tell the time deep underwater, their popularity grew. 

The rate of improvement in the capability of these devices, however, wasn’t just a response to the need. Watchmakers discovered that as they experimented with better seals, the functionality of their watches marched ahead. They found that they were soon able to build devices that far exceeded the limits of unassisted human dives, making them the perfect, reliable accessory. 

When Did Dive Watches Become Official? 

For much of the twentieth century, there were no official dive watch standards. Manufacturers could label a product a dive watch regardless of the depth. In 1996, however, the International Organisation for Standardization defined the current ISO 6425 standard, and it’s been with us ever since. The rule aimed to separate the wheat from the chaff: telling consumers which products are the real deal and those that fail to meet the mark. Thus, those who buy diving watches today know that they are getting timepieces of remarkable robustness.